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(11) | EP 0 053 558 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Vacuum actuator for idle operation control Unterdruckbetätigte Leerlaufregelvorrichtung Dispositif d'actionnement à dépression pour le contrôle du régime de ralenti |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention relates to a vacuum actuator for controlling the idle position of the throttle lever in a vehicle engine.
[0002] Modern automotive vehicles usually must maintain very low engine idle speeds in order to insure proper control of vehicle engine emissions. However, when vehicle accessories are switched on, engines idling at a relatively low speed may stall. Accordingly, it is necessary to provide an actuator which sets the engine idle speed as a function of the load on the engine. Actuators of this type have been proposed before. These devices include a vacuum actuator which is responsive to engine manifold vacuum and which sets a plunger in a predetermined position as a function of the engine manifold vacuum. The plunger acts as a stop forthe engine throttle lever. It is desirable to make the vacuum actuator relatively insensitive to external loads so that such variables as temperature and the strength of the throttle return springs will not affect the operation of the controller.
[0003] Such vacuum actuators are illustrated, for instance, in US-A-3 448 659 and in GB-A-2 020 853. The vacuum actuator shown in this latter prior art reference comprises within a housing a control diaphragm assembly and an actuating diaphragm assembly dividing said housing into a first chamber between the control diaphragm assembly and one end of the housing, a second chamber between the actuating diaphragm assembly and the other end of the housing, and a third chamber between said diaphragm assemblies, said first and second chambers being communicated with vacuum whereas said third chamber is communicated with atmospheric air, first and second resilient means urging said diaphragm assemblies towards each other againstthe respective pressure differentials acting thereacross, a plunger extending from the housing and connected to the actuating diaphragm assembly for being positioned by the latter in an actuating range as a function of the level of vacuum communicated into said actuator, and passage means for establishing communication between the second and third chambers under the control of the control diaphragm assembly, said passage means including an orifice formed in an axial projection of the actuating diaphragm assembly extending toward the control diaphragm assembly, and a valve member slidably received in a cavity defined by an axial projection of the control diaphragm assembly extending opposite the actuating diaphragm assembly, said valve member being urged by a third resilient means toward said orifice and toward a stop defined at the open end of said cavity by the peripheral edge of an opening formed in said control diaphragm assembly.
[0004] Such a prior art vacuum actuator is insensitive to the magnitude of the forces exerted on the plunger. However, this known device has drawbacks when used as a vehicle idle control actuator, since it is desirable, as taught by FR-A-2 315 617 and DE-A-696 437 for actuators of a different design, to avoid that, when the vehicle engine is turned off, the throttle lever be prevented from returning to the fully off position so as to preclude dieseling or engine run-on.
[0005] It is, accordingly, an essential object of the present invention to improve a vacuum actuator of the kind disclosed in GB-A-2 020 853 in such a way that the above discussed drawback be avoided, and this object is achieved, according to the invention, thanks to the fact that the diameter of the axial projection of the actuating diaphragm assembly is less than the diameter of the opening in the control diaphragm assembly so as to permit said axial projection to penetrate into said cavity and thus the plunger to be withdrawn from its actuating range to a fully retracted position when vacuum is no longer available. In a preferred embodiment, the vacuum actuator further "t comprises a stop carried in the housing for limiting movement of the control diaphragm assembly toward the actuating diaphragm assembly such that full penetration of the axial projection of the latter into the cavity of the axial projection of the former effectively corresponds to the fully retracted position for the plunger.
[0006] These and other advantageous features of the invention will become readily apparent from reading the following description of a preferred embodiment, given by way of example only and with reference to the accompanying drawing in which the sole figure is a longitudinal cross- sectional view of a vacuum actuator made pursuant to the teachings of the present invention.
[0007] Referring now to the drawing, the actuator generally indicated by the numeral 10 includes a housing 12 having an inlet 14 which is connected to engine manifold vacuum and another inlet 16 which is communicated to atmospheric pressure. A control diaphragm assembly generally indicated by the numeral 18 and an actuating diaphragm assembly generally indicated by the numeral 20 are mounted within the housing 12 and divide the latter into a first chamber 22 between the assembly 18 and the upper (viewing the figure) end of the housing 12, a second chamber 24 between the assembly 20 and the lower (viewing the figure) end of the housing 12, and a third chamber 26 between the diaphragm assemblies 18 and 20.
[0008] The control diaphragm assembly 1.8 includes an upper diaphragm plate 28 and a lower diaphragm plate 30. Diaphragm plates 28 and 30 clamp a circumferentially extending bead 32 of an annular flexible member 34 which interconnects the diaphragm assembly 18 with the wall of the housing 12. The upper diaphragm plate 28 includes an axially projecting portion 36 which slidably receives a valve member 38. The valve member 38 is urged into engagement with the lower diaphragm plate 30 by a spring 40. The lower diaphragm plate 30 defines an aperture 42 of slightly smaller diameter than the diameter of the valve member 38. The diaphragm assembly 18 is yieldably urged as a unit by a spring 46 toward a radially projecting stop 44 extending from the wall of the housing 12. Upward movement of the diaphragm assembly 18 is limited by engagement of the projecting portion 36 with an adjusting screw 48 installed in the wall of the housing 12.
[0009] The diaphragm assembly 20 includes an upper diaphragm plate 50 which includes a projecting portion 52 which projects toward the control diaphragm assembly 18. Diaphragm assembly 20 further includes a lower diaphragm plate 54 which cooperates with the upper plate 50 to clamp a circumferentially extending bead 56 of an annular flexible member 58. The annular flexible member 58 further includes another circumferentially extending bead 60 which is secured to the wall of the housing 12. A plunger 62 is slidably mounted in a bore 64 defined in the wall of housing 12. One end 66 of the plunger 62 is secured to the lower diaphragm plate 54 of the diaphragm assembly 20 and is movable therewith. The other end 68 of the plunger 62 projects from the housing 12 and is adapted to engage the throttle lever of the vehicle engine to thereby act as a stop limiting retraction of the throttle lever when the throttle return spring (not shown) moves the throttle lever to the idle position. A sealing boot 70 is provided to protect the bore 64 from entry of environmental contaminants. A spring 72 urges the diaphragm assembly 20, and therefore the plunger 62, upwardly viewing the figure toward the control diaphragm assembly 18. As will be described in detail hereinafter, movement of the plunger 62 is controlled by controlling fluid communication through an orifice 74 which extends through the projecting portion 52 and communicates the third chamber 26 with the second chamber 24. A filter is located within the projecting portion 52 to filter the atmospheric air communicated into the chamber 26 when the latter is communicated into the chamber 24. As mentioned hereinabove, atmospheric air is communicated into chamber 26 through the inlet orifice 16, and engine manifold vacuum is communicated into chambers 22 and 24 through the inlet 14 and appropriate control orifices 78, 80.
[0010] The above described actuator operates as follows:
Referring to the drawing, the various components are illustrated in the position which they assume when the vehicle engine is heavily loaded and, accordingly, the engine manifold vacuum level is relatively low, i.e., is quite close to atmospheric pressure. In this condition, the plunger 62 is extended from the housing 12 to its maximum extent (controlled by adjustable stop 81), to thereby limit movement of the afore-mentioned throttle control lever (not shown). If the load on the engine is reduced, the vacuum communicated into the chambers 22 and 24 will be increased, thereby causing the control diaphragm assembly 18 to move upwardly viewing the figure, against the bias of the spring 46. When this occurs, of course, the valve member 38 moves away from the orifice 74, thereby permitting ambient atmospheric air in the chamber 26 to communicate through the orifice 74 and adjacent filter into the chamber 24, thereby reducing the vacuum level therein to permit the spring 72 to urge the diaphragm assembly 20 upwardly viewing the figure. Therefore, the plunger 62 moves into the housing 12, to thereby permit the throttle lever to move to a position further closing the butterfly valve in the engine carburetor to set a lower idle speed than would otherwise occur with a similar load on the vehicle engine. Assuming a constant manifold vacuum, the diaphram assembly 20 will move into position so that the orifice 74 cooperates with the valve member 38 to define a bleed orifice therebetween, thereby permitting just enough ambient atmospheric pressure to communicate into the chamber 24 so that the diaphragm assembly 20 remains in a steady state position.
[0011] If the load on the engine is subsequently increased, thereby reducing the engine manifold vacuum to a value closer to atmospheric pressure, the vacuum level in chamber 22 will be similarly reduced to decrease the pressure differential across the diaphragm assembly 18, thereby permitting the spring 46 to move the diaphragm assembly 18 toward the stop 44. When this occurs, of course, the valve member 38, which can be moved upwardly viewing the figure within the projecting portion 36, sealing engages the orifice 74 to close off communication between the chambers 26 and 24. As a consequence therefrom, the pressure differential across the diaphragm assembly 20 increases due to the fact that the atmospheric bleed through the orifice 74 is shut off. Accordingly, the diaphragm assembly 20 is sucked downwardly viewing the figure in opposition to the spring 72 (and also in opposition to the aforementioned throttle return springs, which are not shown in the drawing, but which also tend to force the plunger 62 upwardly viewing the figure). Accordingly, the plunger 62 is forced out of the housing 12, to thereby stop the throttle lever at an idle position which represents a larger opening in the carburetor butterfly valve (not shown). As discussed hereinabove, the relative positions of the diaphragm assemblies 18 and 20 will reach a steady state position for the new level of engine manifold vacuum such that the orifice 74 cooperates with the position of the diaphragm assembly 20 for a given manifold vacuum level. Consequently, the idle position of the vehicle engine is set at a relatively small butterfly valve opening when the engine is lightly loaded and thereby generates a relatively high vacuum level, because in this condition the engine will idle properly at a small butterfly valve opening. Conversely, when the engine load is increased, thereby reducing the engine manifold vacuum level, the plunger 62 sets an idle butterfly valve opening that is somewhat greater, because the increased fuel flow is necessary to prevent the engine from stalling at these higher loading conditions.
[0012] It will also be noted that the actuating diaphragm assembly 20 follows the control diaphragm assembly 18, but does not exert any load upon it. Accordingly, the control diaphragm assembly 18 is responsive solely to engine manifold vacuum, and is not affected by the force on the plunger 62, since there is no direct connection between the plunger and the diaphragm assembly 18. Accordingly, the actuating diaphragm assembly 20 acts as a fluid motor, communication across which is controlled by the orifice 74 and valve member 38. Therefore, the engine idle speed as set by the idle controller will be a function of the engine manifold vacuum, and will not be affected by such variables, as changes in engine drag or friction, the strength of the throttle return springs (which have a tendency to weaken overtime), and other operating variables.
[0013] When the vehicle engine is turned off, it is necessary to close the butterfly valve of a carburetor so that engine dieseling or run-on is prevented. Accordingly, the size of the opening 42 is made large enough to accommodate the projecting portion 52 of the diaphragm assembly 20, and the stop 44 limits downward movement of the diaphragm assembly 18. Therefore, when the engine is turned off and all of the chambers 22, 26 and 24 are brought to atmospheric pressure, so that the pressure differentials across the diaphragm assemblies 18 and 20 are zero, the spring 46 urges the diaphragm assembly 18 into engagement with the stop 44, and the spring 72 urges the diaphragm assembly 20 upwardly viewing the figure. Because the opening 42 is large enough to accommodate the projecting portion 52, the projecting portion 52 raises the valve member 38 off the lower diaphragm plate 30 to permit the diaphragm assembly 20 to move upwardly viewing the figure as the projecting portion 52 is forced into the projecting portion 36. This is possible, of course, because the spring 40 is much weaker than is the spring 72. Accordingly, the plunger 62 is withdrawn from the actuating range established by the diaphragm assembly 20 when the engine is operating to a fully retracted position in which the upper plate of the diaphragm assembly 20 engages the lower plate 30 of the diaphragm assembly 18 and the projecting portion 52 is fully received within the projecting portion 36.
1. A vacuum actuator for controlling the idle position of the throttle lever in a
vehicle engine, comprising a housing (12), a control diaphragm assembly (18) and an
actuating diaphragm assembly (20) arranged within said housing and dividing same into
a first chamber (22) between the control diaphragm assembly and one end of the housing,
a second chamber (24) between the actuating diaphragm assembly and the other end of
the housing, and a third chamber (26) between said diaphragm assemblies, said first
and second chambers being communicated with vacuum whereas said third chamber is communicated
with atmospheric air, first (46) and second (72) resilient means urging said diaphragm
assemblies toward each other against the respective pressure differentials acting
thereacross, a plunger (62) extending from the housing and connected to the actuating
diaphragm assembly for being positioned by the latter in an actuating range as a function
of the level of vacuum communicated into said actuator, and passage means for establishing
communication between the second and third chambers under the control of the control
diaphragm assembly, said passage means including an orifice (74) formed in an axial
projection (52) of the actuating diaphragm assembly extending toward the control diaphragm
assembly, and a valve member (38) slidably received in a cavity defined by an axial
projection (36) of the control diaphragm assembly extending opposite the actuating
diaphragm assembly, said valve member (38) being urged by a third resilient means
(40) toward said orifice (74) and toward a stop defined at the open end of said cavity
by the peripheral edge of an opening (42) formed in said control diaphragm assembly,
characterized in that the diameter of the axial projection (52) of the actuating diaphragm
assembly (20) is less than the diameter of the opening (42) in the control diaphragm
assembly (18) so as to permit said axial projection (52) to penetrate into said cavity
and thus the plunger (62) to be withdrawn from its actuating range to a fully retracted
position when vacuum is no longer available.
2. A vacuum actuator according to claim 1, characterized in that it further comprises
a stop (44) carried in the housing (12) for limiting movement of the control diaphragm
assembly (18) toward the actuating diaphragm assembly (20) such that full penetration
of the axial projection (52) of the latter into the cavity of the axial projection
(36) of the former corresponds to the fully retracted position for the plunger (62).
1. Un dispositif d'actionnement à dépression pour commander la position de ralenti
du levier du papillon des gaz dans un moteur de véhicule comprenant un boîtier (12),
un ensemble de diaphragme de commande (18) et ùn ensemble de diaphragme d'actionnement
(20) qui sont montés à l'intérieur dudit boîtier et le divisent en une première chambre
(22) formée entre l'ensemble de diaphragme de commande et une première extrémité du
boîtier, une seconde chambre (24) formée entre l'ensemble de diaphragme d'actionnement
et l'autre extrémité du boîtier et une troisième chambre (26) formée entre lesdits
ensembles de diaphragme, lesdites première et seconde chambres étant mises en communication
avec une source de dépression tandis que ladite troisième chambre communique avec
l'air atmosphérique, des premier (46) et second (72) moyens élastiques repoussant
lesdits ensembles de diaphragme l'un vers l'autre à l'encontre des pressions différentielles
respectives qui agissent sur leurs faces opposées, un plongeur (62) s'étendant hors
du boîtier et assemblé à l'ensemble de dipahragme d'actionnement afin d'être positionné
par ce dernier dans un intervalle d'actionnement en fonction du niveau de dépression
transmis audit dispositif d'actionnement, et des moyens de passage pour établir une
communication entre les seconde et troisième chambres sous la commande de l'ensemble
de diaphragme de commande, lesdits moyens de passage comprenant un orifice (74) formé
dans une protubérance axiale (52) de l'ensemble de diaphragme d'actionnement qui s'étend
en direction de l'ensemble de diaphragme de commande et un obturateur (38) monté coulissant
dans une cavité formée dans une protubérance axiale (36) de l'ensemble de diaphragme
de commande qui s'étend en éloignement de l'ensemble de diaphragme d'actionnement,
ledit obturateur (38) étant sollicité par un troisième moyen élastique (40) en direction
dudit orifice (74) et en direction d'une butée formée à l'extrémité ouverte de ladite
cavité par le bord périphérique d'une ouverture (42) formée dans ledit ensemble de
diaphragme de commande, caractérisé en ce que le diamètre de la protubérance axiale
(52) de l'ensemble de diaphragme d'actionnement (20) est inférieur au diamètre de
l'ouverture (42) formée dans l'ensemble de diaphragme de commande (18) de façon à
permettre à ladite protubérance axiale (52) de pénétrer dans ladite cavité et, de
ce fait, au plongeur (62) d'être retiré de son intervalle d'actionnement jusqu'à une
position complètement rétractée lorsqu'une dépression n'est plus fournie.
2. Un dispositif d'actionnement à dépression selon la revendication 1, caractérisé
en ce qu'il comporte, en outre, une butée d'arrêt (44) portée par le boîtier (12)
pour limiter le mouvement de l'ensemble de diaphragme de commande (18) en direction
de l'ensemble de diaphragme d'actionnement (20) de façon que la pleine pénétration
de la protuberance axiale (52) de ce dernier dans la cavité de la protubérance axiale
(36) du premier corresponde à la position complètement rétractée du plongeur (62).
1. Unterdruckbetätigte Vorrichtung zur Regelung der Leerlaufstellung des Drosselklappenhebels
in einem Kraftfahrzeug, mit einem Gehäuse (12), einer Steuermembraneinheit (18) und
einer Betätigungsmembraneinheit (20), die im Inneren des Gehäuses angebracht sind
und es in drei Kammern (22, 24, 26) unterteilen, von denen die erste Kammer (22) zwischen
der Steuermembraneinheit und einem ersten Ende des Gehäuses, die zweite Kammer (24)
zwischen der Betätigungsmembraneinheit und dem anderen Ende des Gehäuses und die dritte
Kammer (26) zwischen den beiden Membraneinheiten gebildet ist, wobei die erste und
zweite Kammer mit einer Unterdruckquelle in Verbindung stehen, während die dritte
Kammer mit der Atmosphäre verbunden ist, ersten (46) und zweiten (72) elastischen
Mitteln, die die Membraneinheiten aufeinander zu drücken, und zwar entgegen den unterschiedlichen
Drükken, die auf ihre gegenüberliegenden Seiten einwirken, einem Plunger (62), der
sich aus dem Gehäuse herauserstreckt und der Betätigungsmembraneinheit so zugeordnet
ist, daß er durch diese innerhalb eines Betätigungsbereiches in Abhängigkeit von der
Größe des an der Betätigungsmembraneinheit anliegenden Unterdrucks positioniert wird,
und einer Strömungsverbindung zwischen der zweiten und dritten Kammer, die unter der
Steuerung der Steuermembraneinheit steht, wobei die Strömungsverbindung eine Öffnung
(74) und ein Verschlußglied (38) aufweist, von denen die Öffnung in einem axialen
Vorsprung (52) der Betätigungsmembraneinheit gebildet ist, der sich in Richtung auf
die Steuermembraneinheit erstreckt, und von denen das Verschlußglied (38) in einem
Raum gleitend gelagert ist, der in einem axialen Vorsprung (36) der Steuermembraneinheit
gebildet ist, der in Verlängerung der Betätigungsmembraneinheit verläuft, wobei das
Verschlußglied (38) durch dritte elastische Mittel (40) in Richtung auf die besagte
Öffnung (74) sowie in Richtung auf einen Anschlag vorgespannt ist, der an dem offenen
Ende des besagten Raumes durch den Außenrand einer Öffnung (42) der Steuermembraneinheit
gebildet ist, dadurch gekennzeichnet, daß der Durchmesser des axialen Vorsprungs (52)
der Betätigungsmembraneinheit (20) kleiner ist als der Durchmesser der Öffnung (42)
der Steuermembraneinheit (18), derart, daß der besagte axiale Vorsprung (52) in den
Hohlraum eindringen kann und aus diesem Grund der Plunger (62) aus seinem Betätigungsbereich
bis zu einer vollständig zurückgezogenen Stellung zurückgezogen werden kann, wenn
kein Unterdruck mehr geliefert wird.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß sie außerdem einen vom
Gehäuse (12) getragenen Begrenzungsanschlag (44) aufweist, der die Bewegung der Steuermembraneinheit
(18) in Richtung auf die Betätigungsmembraneinheit (20) so begrenzt, daß das vollständige
Eindringen des axialen Vorsprungs (52) der Betätigungsmembraneinheit in den Hohlraum
des axialen Vorsprungs (36) der Steuermembraneinheit der vollständig zurückgezogenen
Stellung des Plungers (62) entspricht.